Clinical studies on human breath analysis have discovered that certain trace gases from human breath are correlated to certain diseases, especially for lung-related diseases such as asthma, tuberculosis (TB), and lung cancer (see, M. Philips, et al., Cancer Biomarkers, 3:95-109 (2007); M. Philips, et al., Tuberculosis, 87:44-52 (2007)). In other applications, gas analysis can be used to determine the presence of dangerous substances or fugitive gases, which are incompatible with human presence, such as methane, carbon monoxide or carbon dioxide.
Current gas analytical systems still rely heavily on large and expensive laboratory instruments, such as gas chromatography (GC) and mass spectrometry (MS). Most of these instruments (mass spectrometers in particular) have operational characteristics that prevent significant reductions in their size, meaning that current gas analysis systems are large, expensive devices and are difficult to operate (e.g., laboratory size GC/MS).
In addition to being expensive, the large size of current gas analysis devices makes widespread use of these instruments impossible. Point of care analysis would be highly beneficial, however, no systems are currently available.
Asthma is a chronic lung disease characterized by recurrent episodes of coughing, wheezing, chest tightness and respiratory discomfort. Pulmonary inflammation contributes to the bronchoconstriction that can precipitate an asthma attack, and the progression of this chronic disease. It is estimated that over 20 million people in the United States have asthma. The National Heart Lung and Blood Institute notes that asthma accounts for $16.1 billion in direct and indirect healthcare costs annually.
TB kills roughly two million people every year and is one of the world's best-studied killers. TB diagnostics have remained unchanged for decades, despite their acknowledged poor performance. Current diagnostic methods include sputum smear microscopy, culture, and chest X-rays. However, these methods either have poor sensitivity (45-60% for smear microscopy), poor specificity (˜66% for X-ray), or are too slow (3-6 weeks for culture).
Recent studies show TB tests based on patients' exhaled VOCs and gases of cultured microbacteria have very high sensitivity and specificity using a GC/MS instruments (see, Michael Phillips, et al., Tuberculosis 87:44-52 (2007); Reinhard Fend, J. Clin. Microb., p. 2039-2045 (June 2006)). But this method requires very sophisticated setup and it is not practical to be used in the field.
Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. The majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells. Lung cancer, the most common cause of cancer-related death in men and also the most common in women, is responsible for 1.3 million deaths worldwide annually. The main types of lung cancer are small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC). This distinction is important, because the treatment varies; non-small cell lung carcinoma (NSCLC) is sometimes treated with surgery, while small cell lung carcinoma (SCLC) usually responds better to chemotherapy and radiation.
System and methods are needed which enable human breath analysis for the detection and diagnosis of asthma, tuberculosis and lung cancer. A device is needed for breath analysis and ambient air monitoring that is easy to use, and has high sensitivity and specificity. The present invention satisfies these and other needs.